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FGUS71 KCAR 212139
ESFCAR
MEC003-009-019-021-029-232145-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
439 PM EST Thu Feb 21 2019

...SPRING FLOOD POTENTIAL OUTLOOK FOR NORTHERN... CENTRAL...AND 
DOWNEAST MAINE...

This is the fourth Winter/Spring Flood Potential Outlook for 
2019, issued by the National Weather Service in Caribou, Maine. 
This outlook is for Northern, Central, and Downeast Maine for the 
two-week period of February 21st to March 7th, 2019.

The flood potential for open water flooding and flooding due to 
ice jams is above normal for this time of year for the entire
region.

...CLIMATOLOGICAL GUIDANCE...

During the last two weeks, a few weather systems affected the 
region, with the most significant weather system coming in on the 
13th and 14th. This storm system brought a significant snowfall 
to the region with 7 to 12 inches of snow across the Bangor and 
Downeast region while anywhere from 12 to 18 inches of snow was 
measured across the Maine Central Highlands and Northern Maine. 
This snowfall added to the already existing deep snowpack across 
the Maine Central Highlands and Northern Maine. Caribou set a 
snowfall and precipitation record for the 14th with 12.9 inches of
snow and 0.87 inches of precipitation. 

Over the last two weeks, average temperatures ran slightly below
normal. After a rather mild start for the first week of February 
with above normal temperatures, much colder air worked its way 
into the region bringing average temperatures going below normal.

The weather pattern over the next 7 to 10 days looks to be 
somewhat active. A storm system could bring a significant 
snowfall to the region on the 24th into the 25th, and then there 
appears to be break in the activity into the first day of March. 
Another storm system could affect the region for the first week of
March, but confidence is low on the evolution of this system. 

The official National Weather Service 8 to 14 day outlook is 
calling for below normal temperatures with precipitation expected
to be slightly above normal.

...OBSERVED SNOW DEPTH AND WATER EQUIVALENTS...

Snow depths ranged from 35 to 45 inches across Northern and 
Northwest Maine with a few spots hitting at or above 50 inches. A 
snow depth of 55 inches was measured at Number Nine Mountain in 
Southeast Aroostook County. The town of Guerette, which is north 
of Caribou, came in with 44 inches of snow on the ground. The NWS 
office in Caribou was reporting 39 inches of snow as of 7 AM this 
morning. Snow depths across the Maine Central Highlands ranged 
from 30 to 40 inches with a few locations coming in over 40 
inches. Millinocket Lake recorded 40 inches of snow on the 
ground. The Bangor region including the interior Downeast recorded
12 to 18 inches of snow depth, while the coastal region came in 
with 4 to 8 inches. Snow depths were above normal for most areas 
with the exception of Downeast and the coast, where snow depths 
were averaging near or slightly below normal.

The snow water equivalent, or the amount of water contained in 
the snowpack remains the highest across northern and central areas
with 8 to 12 inches of water measured. The NWS office in Caribou
measured a snow water equivalent of 9.5 inches. Winterville came
in with a snow water equivalent of 11.0 inches. Across the Bangor
and interior Downeast region, 3 to 6 inches of water was 
measured in the snowpack, while the coast came in with 1 to 4 
inches of water. 

The snow water equivalent is above normal for Northern Maine and
the Maine Central Highlands, while from Bangor to the Downeast 
coast, snow water equivalents were near normal. 

...SOIL MOISTURE AND WATER SUPPLY CONDITIONS...

Soil moisture remained above normal across the entire region. The
latest Palmer Drought Severity Index, which measures soil moisture
in the longer term, was showing above normal conditions.

Looking at the groundwater levels, courtesy of the USGS, we  
continue to see the levels above normal. Some sites across the 
Downeast region such as Acadia continued to report high levels.

...RIVER AND ICE CONDITIONS...

River flows remained near to slightly above normal for this time 
of year throughout the region. 

Ice coverage on the rivers across the region was from 95% to 
100%, with some open sections still noted on portions of the 
Piscataquis River and the Penobscot River. The Penobscot River in
the Bangor region remained completely ice covered, but had open 
sections north of Bangor to West Enfield. Ice thickness on the 
Penobscot River varied with 12 to 18 inches measured around 
Bangor. On the northern branch of the Penobscot River at 
Grindstone, the ice thickness was measured to be at 24 inches, or
2 feet. Ice thickness on the Kenduskeag Stream in Bangor was 
measured at 18 inches. The Piscataquis River had open sections in 
Milo. Looking further north, the Fish River near Fort Kent had 
some open water where the streamflow was strong, but completely 
ice covered at the confluence with the St. John River. There was 
open sections noted on the Aroostook River near Ashland where the 
flow is strong. Ice thicknesses increased across the Northern 
Maine rivers. Ice thickness on the Allagash River in Northwest 
Maine was measured to be 12 to 18 inches. Ice thicknesses on the 
St. John River from Fort Kent to Dickey were measured at 6 to 12 
inches, while east of Fort Kent down to Madawaska and Grand Isle, 
ice thicknesses remained estimated at 12 inches. The ice thickness
on the Aroostook River was measured to be around 24 inches, or 2 
feet thick. Ice thickness on the Piscataquis River increased to 
around 14 inches at Dover-Foxcroft.
 
Ice jams remain locked in place on the Northern Maine Rivers. The
ice jam on the Aroostook River from Washburn to Crouseville was 
locked in place. This jam is approximately 7 miles long. Another
ice jam was located on Aroostook River near the Caribou-Fort 
Fairfield town line. Ice jams are locked in place on the St. John
River with a significant ice jam from St. John to St. Francis. 
Other notable ice jams remain on the St. John River from south of 
Fort Kent downstream to the town of Grand Isle.  

Ice coverage and ice thickness is considered to be near normal.
Ice coverage could expand over the next 2 weeks with temperatures
expected to average below normal. This in turn would allow for 
the ice to thicken on the rivers. 

...IN CONCLUSION...

Based on the above information, the flood potential for open water
flooding is above normal across the region. The threat for ice 
jam flooding is above normal.

It is important to remember that a heavy rainfall event along 
with mild temperatures can lead to an increased potential for 
flooding with snowmelt and runoff. Ice breaking up and jamming can
elevate the threat for flooding in a short period of time. 

The next Winter/Spring Flood Outlook will be issued on Thursday,
March 7th.

$$

Hewitt